The present invention relates to a paper loading system which transfers recording paper of a facsimile. In particular, it relates to a method by which to detect a phenomenon in which the recording paper fails to run out, i.e. discharge from said facsimile.
Generally speaking, the facsimile is a device which dissolves an original picture by scanning into picture elements and then changes them into electric signals and transmits those signals to the other party through a medium of transmission and, on the other hand, demodulates those electric signals which are received through the medium of transmission into picture elements and then combines those elements and records them on the recording paper.
In the facsimile, the paper loading system which transfers the recording paper provided to record a received picture is formed as illustrated in FIG. 1. Paper jam means a phenomenon in which the recording paper 10 in the loading system as shown in FIG. 1 fails to run out over the cover 11. It happens mainly from being caught by the cutter 12 or by its peripheral appliances. As to a circuit provided to drive the paper loading system as shown in FIG. 1, it is constructed as illustrated in FIG. 2 and operates in the following manner.
A central processing unit (hereinafter referred to as CPU) 20 drives a DC motor 22 and a step motor 23 through an input/output circuit 21. In addition, it receives output of two photocouplers 14, 15 and senses the remainder of recording paper and detects a paper jam. The input/output circuit 21 drives the DC motor 22 and the step motor 23 under the control of said CPU 20. And, it transmits the output of said two photocouplers 14, 15 to said CPU 20 and, when it drives said DC motor 22, transmits the output of a micro-switch SW which is switch operated by the cutter 12 to said CPU 20. The step motor 23 transfers the recording paper 10 toward the cutter 12 by giving a turn to a recording paper transfer roller 13 at regular angles when the original picture is received, and the DC motor 22 operates the cutter 12 to cut the recording paper. The photocoupler 14 detects if the recording paper is transferred when the original picture is received. The photocoupler 15 detects if there is a remainder of the recording paper. In the drawing, 16 is a printer head and 17 is a paper feeding roller.
A conventional method which has been heretofore used to detect the paper jam caused in the paper loading system in FIG. 1 which is driven by the circuit of FIG. 2 is carried out according to a flowchart of FIG. 3. Now, a description of FIG. 3 will be made as follows.
When the original picture is received, the CPU 20 drives the step motor 23 through the input/output circuit 21 and transfers the recording paper and, on the other hand, receives the output of photocoupler 14 used as a jam detection sensor through the input/output circuit 21 (step 30). After said step 30 is over, the CPU 20 checks if the output of said photocoupler 14 is in the high logic condition and determines whether there is recording paper (step 31). That is, it checks whether the recording paper transfer operation has come to an end. In the event that no recording paper exists in the high logic condition of said photocoupler 14 output at said step 31, the CPU 20 checks if page reception time is over and, when said page reception time is not over, returns to the previous step (step 32). Step 33 displays the occurrence of paper jam, and step 34 has the cutter 12 cut the recording paper. However, such a method as described hereinabove requires a photocoupler 14 used as a paper jam detection sensor. Thus, it involves a problem in that a design for circuits is made complicated by the arrangement of a printer keyboard and connecting wires.
Consequently, the object of the present invention is to provide a paper jam detection method in which a design for the circuit can be simplified by detecting the present condition of the paper without a jam detection sensor, in a facsimile employing rolled recording paper.